The invention is directed to forming a fiber tearing adhesive bond to metallized polymer film.
Metallized polymer films are increasingly being used as packaging materials. Many packaging applications require the package to be sealed with an adhesive composition. This presents a problem for applications in which the packaging material includes a metallized polymer film, because it is very difficult to form an adhesive bond to a metallized polymer film. Adhesive compositions often exhibit adhesive failure at the interface between the metallized film and the adhesive composition. In many applications, adhesive failure is unacceptable because the packaging is designed with the expectation that the adhesive composition will maintain a sufficiently strong bond to the metallized film until the package is opened. In many of these packaging applications, the adhesive bond must be stronger than the substrates being bonded such that when the package is opened at the adhesive seal, one or more of the bonded substrates tear. The difficulty associated with forming a sufficient adhesive bond to a metallized polymer film is exacerbated in packages that contain relatively heavy contents such as dry pet food, e.g., dog and cat food.